김윤희 교수

We analyze the combined influence of the interchannel and intersymbol interferences, which result from the time variation and delay spread of mobile channels, on the performance of an orthogonal frequency-division multiplexing (OFDM) system. Both analysis and simulation results are presented for uncoded 16-QAM. We also investigate the performance of a Reed-Solomon (RS) coded 16-QAM OFDM system when the number of subcarriers varies: it is observed that there is an optimum number of subcarriers th

In this paper, we propose a new frequency synchronization algorithm for orthogonal frequency division multiplexing (OFDM) systems requiring only one training symbol, based on a conventional method which requires two training symbols. While the timing synchronization is obtained by using the conventional method, the carrier frequency offset is efficiently estimated by the proposed method. It is shown that the proposed method not only reduces the number of the training symbols but also possesses b

Multicarrier transmission schemes have been introduced into code-division multiple access (CDMA) systems to gain advantages for high data rate transmission. One of the methods is to transmit identical narrowband direct-sequence (DS) waveforms in parallel over a number of subchannels using frequency diversity. In this paper, we propose a multicarrier CDMA system with an adaptive subchannel allocation method for forward links. In the proposed system, instead of identical DS waveforms being transmi

In this paper, by modifying a conventional method which requires two training symbols, we propose a timing and frequency synchronization algorithm for OFDM systems which requires one training symbol. While the frame/symbol timing is obtained by using the conventional method, the carrier frequency offset is efficiently estimated by the proposed method. Key features of the proposed method are presented in terms of missing probability and estimation error variance of the carrier frequency offset es

We consider a two-phase decode-and-forward (DF) relay network assisted by an unmanned aerial vehicle (UAV), where the UAV performs energy harvesting and information decoding simultaneously with a power splitting (PS) receiver structure. For the network, we optimize the PS and time allocation (TA) factors to minimize the outage probability in transferring the data from a source to a destination suffering from blockages in the direct link. The optimal solution is found in two steps, optimization o

1. Objective The object of this study was to understand the clinical characteristics of the Taeeumin Symptomatic Pattem. 2. Methods The patients visiting the department of Sasang Constitution of Traditional Korean Medicine clinic from June to November of 2008 were used in this study. Those who showed a favorable turn after over ten days of medication and who showed up for at least two follow-up sessions were chosen among first-time visitors. Of these, 75 patients identified and verified to be of

Purpose: The purpose of this study was to identify mental health state and family function of the parents with a mentally disabled person by comparison to the parents with a normal person. Methods:Data was collected from 116 parents with a mentally disabled person and 122 parents with a normal person living in Seoul and Gyeonggi province from April 10, 2008 to January 10, 2009 by using the survey instruments. Results: Psychiatric symptoms (t = 4.27, p < .001) and personality patterns (t = 3.52,

Changing consumption patterns and increasing health awareness, especially in Europe, are resulting in an increased demand for sesame seeds. In 2016, Asia imported the highest quantity of sesame seeds, followed by Europe and North America. We examined, for the first time, the effects of treatment with sesame oil and sesamin in hearing impairment models. Sesame oil exhibited an ameliorative effect on auditory impairment in a hair cell line in zebrafish and mice. In ototoxic zebrafish larvae, neuro

1. Objectives We had been developing a 3D Automatic Face Recognition Apparatus (3D-AFRA) in order to evaluate the external appearances with more objectivity. This apparatus provides a 3D image and numerical data on facial configuration, and this study aims to evaluate the accuracy of 3D-AFRA recognition. 2. Methods Each scanned pictures were pointed with the 3D Automatic Face Recognition Apparatus(3D-AFRA). And the results were compared with data pointed pictures with manual. And we analysed the

Recently, intelligent reflecting surfaces (IRSs) have drawn huge attention as a promising solution for 6G networks to enhance diverse performance metrics in a cost-effective way. For massive connectivity toward a higher spectral efficiency, we address an intelligent reflecting surface (IRS) to an uplink nonorthogonal multiple access (NOMA) network supported by a multiantenna receiver. We maximize the sum rate of the IRS-aided NOMA network by optimizing the IRS reflection pattern under unit modul

In this paper, we propose an LDPC-coded OFDMA system with a resource allocation method suitable for the uplink of mobile cellular environments. At the receiver of the proposed system, an iterative channel estimation and decoding (IED) method with a Wiener filter adapting to the channel variation rate is employed to support high mobility without boosting the pilot power. For practical applications, the channel variation rate is also estimated with pilot symbols to select Wiener filter coefficient

In this paper, we propose to transmit convolutionally coded DS waveforms over orthogonally overlapped subchannels in time limited asynchronous channels. The bit error rate of the decoder output is investigated along with simulation results under several conditions on the channel state information (CSI). It is shown that the proposed system, the convolutionally coded orthogonal multicarrier DS/CDMA system, significantly outperforms the system using frequency diversity combining. It is also shown

This letter studies deep learning methods for beam selection in multiuser beamforming with limited feedback. We construct a set of orthogonal random beams and allocate the beams to users to maximize the sum rate, based on limited feedback regarding the channel power on the orthogonal beams. We formulate the beam allocation problem as a classification or a regression task using a deep neural network (DNN). The results demonstrate that the DNN-based methods achieve higher sum rates than a conventi

본고는 사회적 주체로서의 자기 인식이 약한 지방대 학생들로 하여금 사회 문제를 문제로서 인식할 수 있도록 하기 위해 대학이 해야 할 일은 무엇인가에 대한 고민에서 출발하였다. 경쟁 구도 속에 있는 대한민국의 정규교육과정에서 만성적인 열패감을 경험할 수밖에 없었던 지방대 학생들은 수도권 중심으로 형성된문화 자본으로 인하여 대학 입학과 동시에 또 다시 사회 중심으로부터 밀려났다는 생각에 자비심(自卑心)을 가질 수밖에 없게 된다. 그러다 보니 이들은 한 사회의 성원으로서의 권리와 책임 의식이 약해 사회통합감이 낮다. 다양한 사회문화적 요인들로 인하여 자기 안에 갇혀 있는 이들의 자아 경계 영역을 허물고, 공동체를 ‘우리’로 인식하게 하기 위해서는 감정 이입을 통해 타자의 고통에 대한감수성을 확대할 수 있는 글쓰기 교육이 중요하다. 특히 낮은 자존감으로 인하여자신을 드러내는 것을 두려워하는 이들에게 있어 영화를 보고 쓰는 비평문은 스스로를 감추면서 드러나게 한다. 이때 주어진 영화가 그들이